Concave disc



FIG. 1 is a perspective view of a concave disc showing our new design;

FIG. 2 is a front view thereof;

FIG. 3 is a back view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The broken line showing of the hook and eye portion in FIGS. 1-7 is included for the purpose of illustrating environmental structure and forms no part of the claimed design. 

The ornamental design for a concave disc, as shown and described. 